From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4EC25C55199 for ; Mon, 27 Apr 2020 09:30:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2DECB206A4 for ; Mon, 27 Apr 2020 09:30:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726866AbgD0Jas (ORCPT ); Mon, 27 Apr 2020 05:30:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43948 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726700AbgD0Jap (ORCPT ); Mon, 27 Apr 2020 05:30:45 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1A4C7C0610D5 for ; Mon, 27 Apr 2020 02:30:45 -0700 (PDT) Received: from p5de0bf0b.dip0.t-ipconnect.de ([93.224.191.11] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jT066-0007bt-7C; Mon, 27 Apr 2020 11:30:42 +0200 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id 3838B100606; Mon, 27 Apr 2020 11:30:41 +0200 (CEST) From: Thomas Gleixner To: Leonid Bloch , linux-kernel@vger.kernel.org Cc: John Stultz , Stephen Boyd , Leonid Bloch Subject: Re: [PATCH] rtc: Do not sync CMOS clock when CONFIG_RTC_SYSTOHC is not set In-Reply-To: <20200426013521.43087-1-lb.workbox@gmail.com> References: <20200426013521.43087-1-lb.workbox@gmail.com> Date: Mon, 27 Apr 2020 11:30:41 +0200 Message-ID: <875zdls2bi.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Leonid Bloch writes: > According to documentation in 'drivers/rtc/Kconfig', if > 'CONFIG_RTC_SYSTOHC' is set, then: > > ''' > The system time (wall clock) will be stored in the RTC specified by > RTC_HCTOSYS_DEVICE approximately every 11 minutes if userspace reports > synchronized NTP status. > ''' > > However in reality, even if 'CONFIG_RTC_SYSTOHC' is not set, the RTC > is still sometimes synced with the system time: at least when the RTC > driver is 'rtc_cmos', in certain situations. This commit prevents > that. But in reality sync_cmos_clock() depends on CONFIG_GENERIC_CMOS_UPDATE and has nothing to do with CONFIG_RTC_SYSTOHC. That's a historical leftover from the days where RTCs were strictly a platform/architecture specific issue. Your change would break all architectures which still depend on that. Thanks, tglx